Homeworld Effects Manual: setDeltaColorA()
setDeltaColorA(float red, float green, float blue, float alpha)
Useful range of values: (-1, 1) for all four variables
Default values: (0,0,0,0)
setColorA() takes a single RBGA variable as input, but setDeltaColorA() takes four floats. The range 0 - 1 for one of setDeltaColorA()'s variables corresponds to the range 0 - 255 for one of the components of setColorA()'s variable. Each of setDeltaColorA()'s variables indicates how much each component of the ColorA attribute will change per second. Since they represent change, red, green, blue, and alpha can be positive or negative.
Setting the Lighting attribute disables the ColorA attribute, so setLighting(1) renders this command useless.